The current problem is how to effectively dry/dehydrate the output from a wet milling operation, through a continuous process, while maintaining the integrity of the original food without corrupting its nutritional value. The inventors first encountered this problem while investigating ways to recover avocado pulp, a byproduct of avocado oil extraction, into a stable form with a long shelf life and easily transportable. The inventors considered freezing the wet milling pulp but it was ruled out as impractical and too expensive.
Drying the avocado pulp seemed to be the only viable alternative to achieve a food product with a long shelf life and easily transportable, and also meet other important criteria, including: preservation of nutritional content, original color, long shelf life and be produced in an economical continuous fashion.
In searching for processes on drying the avocado pulp, it appears that four main technologies are used in the food drying industry: freeze drying, conventional drying, vacuum drying and osmotic drying.
Freeze drying and conventional drying technologies are the most widely used technologies in the commercial realm. Oven drying, tunnel drying, spray drying and drum drying are considered conventional drying methods, through the direct use of heat, and are extensively used commercially. Some also have used microwaves to dry food, however, this technology falls under the conventional drying realm.
Freeze drying is a costly alternative that requires large amounts of capital to implement and is a high energy consumer during processing. While this method is less intrusive on the integrity of the end product, when compared to conventional methods, three obstacles became evident:                1) Long drying process.        2) Energy intensive due to the freezing of the pulp and operating the vacuums needed to extract water from the frozen matter.        3) Very expensive to implement.        
Conventional Drying also suffers from several serious drawbacks.                1) The use of high heat during dehydration has severe affects on the nutritional integrity of the end product        2) Energy intensive process.        3) The process discolors the milled pulp.        4) Harsh chemicals are necessary to clean the drying surfaces during the process.        5) In the case of spray drying it is costly to implement.        
Vacuum and Osmotic drying do not lend themselves to the dehydration of wet milled material in a continuous process.
Thus there is a need for methods and apparatus for recovery of milled avocado pulp or paste that can be dried/dehydrated in a continuous fashion with no compromise in the nutritional value of the end food product, and should also be economical and preserve the original pulp color. Also, when reconstituted, maintains the nutritional and sensory profile of the original food product